PYRAMID. A solid structure, usually of stone, having a square base and triangular sides meeting in an apex. True pyramids are found only in Middle Egypt, and date from the period between the Fourth and Twelfth dynasties, though a few may be somewhat older. Pyramidal occur elsewhere. but they differ in im portant particulars. The pyramids of Mexico, for example. have flat tops and the sides form successive stages or steps. Those of Abydos and Merot; are merely imitations of pyramids on a small scale; they are really sepulchral chambers having the pyramidal form externally, and are usually provided with porticoes repre senting the funerary chapels of older tombs. The pyramids found at Cenchrex and at Rome are sporadic attempts to reproduce the Egyptian type.
With regard to the mode of construction of the pyramids of Egypt, two principal theories have been advanced. Lepsins, followed by Ehers. and more recently by Borchardt. believed that each king. on ascending the throne. began to build a pyramid as a tomb and monument for himself. This was usually laid out upon a comparatively small scale, so that if the builder had but a short reign his tomb might be com plete. _\s time passed. successive layers were added, and the size of the monument was thus proportioned to the length of the builder's reign. This theory is combated by Petrie (q.v.). who be lieves that each pyramid was begun and carried out upon a definite design of size and arrangement. The plan was occasionally altered. but in such cases the alteration was not gradual, but sudden. The outer casing of the pyramids was invariably of massive blocks of fine stone, well joined, and carefully polished. The interior of the mass varied at different periods. In the oldest pyramids it was formed, so far as is known. of courses of rough-hewn blocks laid with a little mortar. In later times the core was formed of brick and rubble inclosed between inner and outer walls of solid masonry, and under the Twelfth Dynasty the core is almost entirely of sun-dried bricks. Each pyramid contained a sepulchral chamber was always low down, and was usually excavated in the rock underly ing the structure. It was reached by a passage opening from the northern face of the pyramid and passing, in its course, through one or more lesser chambers. The external entrance was usually situated above the level of the sepulchral chamber, and the passage sloped downward at a moderate angle. Pyramids seem to have stood originally within walled inclosures, and traces of the walls are still to be found in many cases. To each pyramid was attached a temple in which the funerary worship of the deceased Pharaoh was conducted by priests who were supported by a regular endowment. Such temples are still to be seen at Ghizeh, and the priests of the various pyramids are frequently mentioned in the Egyp tian inscriptions. Around the pyramid of each king are grouped the tombs (mastabas) of the nobles and high functionaries who had lived under his reign.
The pyramids that now exist in Egypt. some seventy-five in number, extend in groups from Abu Do5sh on the north to Aledum on the south. The group of Abu Rofish consists of three pyramids all ruined ; the largest of them has lost its outer casing, and is now a shapeless mass of Nile mud inclosing a nucleus of massive stone. One of the others still contains a sepul chral chamber and the passage leading to it. Farther to the south lies the group of Ghizeh, by far the most important among the Egyptian pyramids. The largest of the group is the Great Pyramid, the tomb of Cheops (q.v.), the second
King of the Fourth Dynasty. It was called by the Egyptians Yeeluret Chnfa, 'the glory of Chufu' (C'heops). Its present perpendicular height is 451 feet, but originally, including the nucleus of rock at the bottom and the apex which has disappeared. it measured 482 feet, or more than 50 feet higher than Saint Peter's at Rome. The sloping sides. which rise at an angle of 51° 50', are now 568 feet in slant height and have a length of 750 feet at the base. The cubic contents amount to about 3,057,000 cubic yards. representing a weight of no less than (1.848.000 tons. According to Petrie's estimate, the pyramid contains about 2,300,000 blocks of stone averaging some 40 cubic feet in size. In its present condition this immense edifice covers a space of nearly thirteen acres. The material of which it is constructed consists of stone from the Mokattam and Tura hills on the opposite side of the Nile. Traces of the road by which the stone was conveyed are still visible. The outer casing of this pyramid has long since disappeared, and the underlying courses of rough hewn stone now form a series of steps. The en trance is in the north face of the pyramid at the height of about 4S feet from the ground. From it there was a narrow passage, 3 feet 4 inches high by 3 feet 11 inches wide, which, after descending into the interior at an angle of 26° 41' for a distance of 293 feet, terminates in a horizontal corridor, 27 feet long, 3 feet high, and 2 feet wide, leading to a subterranean cham ber hewn in the solid rock. This chamber is 46 feet long, 27 feet wide, and feet high. Its floor lies feet below the level upon which the pyramid is built, and a blind passage opens from its farther end. Some 60 feet from the external entrance a second passage branches off from the long descending passage and ascends at about an equal angle for a distance of 121 feet, when it enters the Great Hall. At this point a horizontal corridor leads from the ascend ing passage to the so-called Chamber of the Queens. which is 17 feet long, 18 feet 10 inches wide, and 20 feet high, The Great Hall, which continues the ascending passage, is 2S feet high and 155 feet long, but is very narrow. the width of the lower part being 3 feet 4 inches. and that of the upper part only 2 feet 7 inches. It ter minates in a horizontal passage 122 feet long and 3 feet S inches high, expanding about the middle into an antechamber. At the end of the horizontal passage is the King's Chamber, the most remarkable of all the chambers in the pyramid. The .northern and southern sides are each 17 feet in length, the eastern and western sides feet, and the height is 19 feet. The floor is 13914 feet above the plateau upon which the pyramid stands. The chamber is lined with finely polished granite slabs, and the ceiling is formed of nine great blocks of granite, each 1814 feet long. Within the chamber is a mu tilated stone sarcophagus, the lid of which has disappeared. In order to relieve the roof of the pressure of the superincumbent mass of masonry, five hollow chambers have been constructed above it. The first four have fiat ceilings, while the last is roofed with blocks bearing obliquely against each other. Two air shafts (8X6 inches) run from the King's Chamber to the northern and southern faces of the pyramid. Near the Great Pyramid, on the east side, are three small pyramids built for members of Cheops's family; a few hundred yards to the southeast is the Sphinx (q.v.).